1. Field of the Invention
The present invention relates to a misalignment detection device, and more particularly, to a misalignment detection device applied in pressure exerted on an integrated circuit and at least one substrates.
2. Description of the Related Art
In nowadays electronic devices, elements are connected to a major circuit through conductive films, such as anisotropic conductive films (ACFs), which are formed by mixing non-conductive resins and conductive particles. FIG. 1A is a cross-sectional view of a conductive particle 1. The diameter of the conductive particle 1 is about 3 μm to about 5 μm. The center portion 1a of the conductive particle 1 is formed by a polymer, and the conductive particle 1 is covered externally by a metal conductor 1b, such as gold, silver, nickel, tin, copper, or the like.
ACFs are typically used for the manufacture of displays. In a manufacturing method, an ACF is used to directly dispose the driving chips of a panel on a glass substrate, known as the Chip-On-Glass (COG) procedure or an ACF is used to dispose the driving chips on a flexible printed circuit (FPC), known as the Chip-On-Film (COF) afterward the FPC is electrically coupled to a substrate. In addition, an ACF is used to dispose the driving chips on a printed circuit board (PCB), known as the Chip-On-Board (COB).
FIG. 1B shows pressure between a substrate and a driving chip through an ACF. Referring to FIG. 1B, a substrate 10 can be a glass substrate, an FPC, a PCB, or other circuit boards. During manufacture, metal pads 10a are formed on the substrate 10 to transmit signals or power, such as voltage level, current, or likes. Thick bumps 11a are formed on pins of the driving chip 11. An ACF 12 is then disposed between the driving chip 11 and the substrate 10. ACF 12 is heated to increase adhesion capability, and then applying a pressure on the driving chip 11 and the substrate 10 so as to assembly. Note that the pads 10a and the corresponding bumps 11a must be aligned.
Since each bump 11a has a fixed thickness, conductive particles 1 are compressed between the pads 10a and the bumps 11a. Through metal conductors 1b externally covering the conductive particles 1, the compressed conductive particles 1 electrically connected to the bumps 11a and the pads 10a. Thus, the motion of the driving chip 11 and the coupling of circuits are performed at the same time by ACFs.
During manufacture, the accuracy of disposition alignment is determined by the naked eye of the operator, thus, a great number of detection operators is required. Moreover, the accuracy of disposition alignment may be suffered due to erroneous detection by operators or an insufficient sampling rate.
As shown in FIG. 2A, the misalignment occurs between the bump 11a of the driving chip 11 and the pad 10a of the substrate 10. The bump 11a is electrically connected to a pad adjacent to the corresponding pad 10a, and the misalignment thus occurs. In another case as shown in FIG. 2B, although the bump 11a is not electrically connected to the next pad, a short path is formed between the bump 11a and the pad adjacent to the corresponding pad 10a via the conductive particle 1. If erroneous or incomplete detection occurred by the operators leading to produce the defective products.